Features support

Currently taxonomy_single_tag stores which vocabularies are configured for single tag by using a variable that stores vocabular IDs. While there's nothing particularly wrong with this approach, the use of arbitrary IDs makes exporting such a configuration problematic. Integrating with features' use of machine names, or perhaps better, the using the Ctools exportables API to provide defaults via code might be better.

In the mean time, I've implemented a small, hackish patch which stores the single tag setting for vocabularies that have features-provided machine names in a named variable that can be exported with features using strongarm. Let me be clear: this is a hack, and I do not believe this is the best long-term solution for the module; however, it's a serviceable workaround for now.